Could be any number of things. Temperature differences. Pressure differences. Solar influence re: time of day illumination on air masses. The point is that radars aren’t powerful enough, not ionizing radiation and the Doppler inclusion is just straight up BS.
Do those variables often create a wall that stops weather patterns from advancing?
Are you assuming that electromagnetic waves created by radar cannot be amplified by quantum time reversal?
Why does the federal government require reports of weather modification by “a laser or other sources of electromagnetic radiation”, if such is impossible?